The definition of an Ultra Marathon is a running race that is longer than 26.2 miles. Most are 50 or 100 mile events. With this in mind, speed does not become the most important factor for training principles. The most important element to finishing an ultra is one's ability to last and finish without wearing the body out.

Most ultra events take place on trails in extreme natural environments or over any mountainous terrain. Hydration is very important in providing the body with the needed fluids.

In January 2014, a new AK Race Vest 2.0 was released by Ultimate Direction. The AK Race Vest 2.0 was designed by the champion of minimalism - Anton Krupicka.

The AK Race Vest 2.0 gives you everything you need with innovative fabrics and design that come together to provide the ultimate in lightweight comfort. It weighs only 7 ounces and it won't hold you back and gives you liters of storage.

Version 2.0 increases durability by switching to Silnylon from Cuben Fiber, using a stronger 340 gm Power Mesh, adding edge banding to the upper strap pockets, and making the bungee cord stronger. The lower main compartment pockets are gone and the back panel is cut higher for better gear storage and retention.

This is the pack that's used all over the world, for the easy hour run to the hundred miler run.